Flavonoids are widely distributed polyphenolic compounds in the diet that possess various health-promoting effects. This study aimed to investigate the association between dietary flavonoid intake and all-cause and cardiovascular mortality in adults.The data on the six main subclasses of flavonoids, including isoflavones, anthocyanidins, flavan-3-ols, flavanones, flavones, and flavonols, were obtained from the 2007-2010 National Health and Nutrition Examination Survey (NHANES) dataset of adults. The participants were followed up until December 30, 2019. Cox regression models were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for dietary flavonoid intake and mortality. The study included a total of 8758 adults (mean age 44.00 years; 47.40% men). A median follow-up of 10.7 years yielded 1113 all-cause deaths and 261 cardiovascular deaths were recorded. In comparison to category 1, category 4 of flavan-3-ols, flavonols, and total flavonoids were associated with lower risks of all-cause mortality, with multivariable-adjusted HRs of 0.71 (95% CI: 0.55-0.92, Ptrend = 0.021), 0.58 (95% CI: 0.45-0.74, Ptrend<0.001), and 0.63 (95% CI: 0.50-0.80, Ptrend = 0.010), respectively. Similarly, higher intake of category 4 flavonoids was associated with a reduced risk of cardiovascular mortality, with HRs of 0.68 (95% CI: 0.29-0.89, Ptrend = 0.035) for flavones, 0.41 (95% CI: 0.22-0.78, Ptrend = 0.001) for flavonols, and 0.54 (95% CI: 0.36-0.80, Ptrend = 0.021) for total flavonoids.Dietary flavonoid intake is associated with all-cause and cardiovascular mortality. Increasing dietary flavonoid intake may reduce the risk of death in adults.Copyright © 2024 European Society for Clinical Nutrition and Metabolism. Published by Elsevier Ltd. All rights reserved.